<template>
  <div>
    <router-link tag="div"
                 to="/"
                 class="header-abs"
                 v-show="showAbs"
    >
      <div class="iconfont header-abs-back">&#xe63c;</div>
    </router-link>
    <div class="header-fixed"
         v-show="!showAbs"
         :style="opacityStyle"
    >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe63c;景点详情</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
  export default {
    name: "DetailHeader",
    data(){
      return{
        showAbs:true,
        opacityStyle: {
          opacity : 0
        }
      }
    },
    activated() {
      window.addEventListener('scroll',this.handleScroll)
    },
    deactivated() {
      window.removeEventListener('scroll',this.handleScroll)
    },
    methods:{
      handleScroll(){
        const top = document.documentElement.scrollTop
        if (top>60){
          let opacity = top/140
          opacity = opacity >1 ? 1 : opacity
          this.opacityStyle = {
            opacity
          }
          this.showAbs = false
        }else{
          this.showAbs = true
        }
      }
    }
  }
</script>

<style lang="stylus" scoped>
  @import "~styles/variable.styl"
  .header-abs
    position absolute
    left .2rem
    top .2rem
    height .8rem
    line-height .8rem
    width .8rem
    text-align center
    border-radius .4rem
    background: rgba(0,0,0,0.8)
    .header-abs-back
      color #ffffff
      font-size:.4rem
  .header-fixed
    z-index 2
    height $headerHeight
    line-height $headerHeight
    text-align center
    color #ffffff
    overflow hidden
    background: $bgColor
    font-size .32rem
    position fixed
    top 0
    height $headerHeight
    left 0
    right: 0
    .header-fixed-back
      width: .64rem
      position absolute
      font-size .4rem
      text-align center
      left 0
      top 0
      color #fff
</style>
